05/05/2011

Astronomy Day 2011

The Crescent Moon. Credit: Lisa/WWSkies/SXC

This year, Astronomy Day was moved from April, where it has been Earth Day’s neighbor, to the first Saturday in May. There are a number of ways for you to celebrate, from visiting a planetarium or observatory to reading a good astronomy book. But the best way, of course, is to go outside on Saturday night, gaze at the stars, and invite others to join you.

Saturday, May 7, was a good choice for Astronomy Day (or Night). After sunset, you can find a slim crescent moon setting in the west. The crescent moon is the best target for any telescope because its nearness to us allows us to see stark relief in the lunar mountains and valleys. The moon is positioned between the twins of Gemini and above Orion and Taurus, which will set before the moon. Once you’ve explored the contours of the moon, shift your telescope to the upper left to find the center of the constellation Cancer. A star cluster known as the Beehive is the highlight of this region. Tracing this path through the Zodiac constellations farther back on the sky we come to the backward question-mark shape of Leo the Lion with its bright star Regulus, and behind Leo is the next dazzling telescopic target, Saturn. On the evening of May 7, Saturn will be just over a degree away from Porrima, a 3.4-magnitude star in Virgo. Through a telescope, you’ll see that a magnitude 5.9 star is even closer, halfway between Saturn and Porrima.

A telescope should allow you to easily spot Saturn’s rings and perhaps its largest moon as well, Titan. Titan is the only known satellite with a substantial atmosphere, and it’s also host to liquid methane and ethane lakes and wind and rain. Its surface temperature feels like a frigid -240 degrees Fahrenheit. If the weather here on Earth is cloudy or rainy for Saturday, try Friday or Sunday, for similar views of a crescent moon and Saturn.

-- Kelly Kizer Whitt loves clean, clear, and dark skies. Kelly studied English and Astronomy at the University of Wisconsin-Madison and worked for Astronomy magazine. She is currently the Feature Writer for Astronomy and Space at Suite101.com. You can follow her on Twitter at twitter.com/Astronomommy.

User comments or postings reflect the opinions of the responsible contributor only, and do not reflect the viewpoint of the Sierra Club. The Sierra Club does not endorse or guarantee the accuracy of any posting. The Sierra Club accepts no obligation to review every posting, but reserves the right (but not the obligation) to delete postings that may be considered offensive, illegal or inappropriate.